Two-phase stepper motor driven toys

ABSTRACT

The present invention relates to a two-phase stepper motor driven toy comprising a toy body having at least one movable member; a transmission mechanism operatively coupled to said at least movable member; an electric drive means for driving said at least movable member which includes a motor control circuitry for generating electrical signals and a two-phase stepper motor operating in response to the generated electrical signals; and a battery power unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional application No. 60/679,234, filed May 10, 2005.

FIELD OF THE INVENTION

This invention relates generally to motion toys and, more particularly, to toys which use a two-phase stepper motor as a driver and can perform some preset actions.

BACKGROUND OF THE INVENTION

Many motion toys, such as toy cars etc., can be controlled to move forwards/backwards and in other direction. One such toy car is disclosed in U.S. Pat. No. 6,250,987B1 to Choi, entitled “Programmable Toy”. This toy car is controlled by pressing appropriate keypad buttons to perform a series of preset actions, and is a remote-controlled one.

U.S. Pat. No. 6,505,527 discloses a forward/backward steering control mechanism for a remote-controlled toy car, which uses a simple gear clutch structure to control switching between forward mode and backward mode of the remote-controlled toy car. As far as such a toy car is concerned, except for necessary remote-controller, the structure of this forward/backward steering control mechanism, obviously, is complicated.

A Go-Kart without use of a remote controller, manufactured by MANI INDUSTRIES LTD., is available in the market. This Go-Kart is driven by means of a DC motor. Further, the use of an auxiliary wheel results in change of the traveling direction. However, such a Go-Kart is relatively large in size and reduces the entertainment value due to its monotonous motion.

Therefore, the present invention is directed to provision of a simply constructed motion toy without use of a remote control means and to enhancement of the entertainment value of motion toys in existence. The motion toy according to the present invention employs a two-phase stepper motor, allowing the toys to move in a forward or backward direction without the need of additional sensors and/or mechanisms to detect a collision, such that the toy may be easily and efficiently manufactured and marketed with a reasonable price for retail sale.

SUMMARY OF THE INVENTION

In accordance with the present invention, there is provided a two-phase stepper motor driven toy which changes its movement direction upon collision against an obstacle, without the need of additional sensory mechanisms and any remote-control devices.

To attain this, the two-phase stepper motor driven toy comprises:

a toy body;

at least one movable member movably mounted to said toy body;

a transmission mechanism operatively coupled to said at least movable member;

an electric drive means for driving said at least movable member via said transmission mechanism;

a battery power unit for providing power to said drive means;

wherein said electrical drive means includes:

a motor control circuitry for generating electrical signals in accordance with preset modes; and

a two-phase stepper motor, which is electrically connected to said motor control circuitry to selectably regulate the operational modes of the two-phase stepper motor in response to the generated electrical signals, for translating the rotational motion via said transmission mechanism to actuate motion of said at least movable member of the toy.

Referring to the motor control circuitry, it is preferably a micro control unit or a microprocessor or the like, which may be programmed to operate the two-phase stepper motor to move said at least one movable member in a manner permitting said member to be moved in a forward or backward direction.

According to the present invention, the two-phase stepper motor is controlled to behave in various operational modes, i.e. “persistent mode”, “bounce mode 1”, “bounce mode 2” and “quiver mode”, which provides an easy implementation for automatic regulation of direction change of a motion. The operational modes and speed of the two-phase stepper motor may be controlled by varying the period of the electrical signals generated from the motor control circuitry.

The two-phase stepper motor is a very small, lower power electric motor that is effective to drive all the movable members of the toy for their movements in a controlled manner while keeping the toy economical and minimizing its power requirement to provide acceptable battery life for the toy. In addition, the use of the two-phase stepper motor allows the toy to be very compact and relatively inexpensive.

For translating the rotational motion caused by the two-phase stepper motor into lineal or rotational movement of the moveable members, some conventional transmission mechanisms need to be used in order to drive the movable member(s) at an appropriate speed.

The battery used in the battery power unit is preferably a button cell, which make the toy relatively small in size.

In accordance with one embodiment of the present invention, the toy body is a toy vehicle body, which is mounted on a chassis equipped with four movable members: a pair of front wheels and a pair of rear wheels. Alternatively, a freely rotating wheel is arranged centrally and somewhat forwardly underneath the chassis of the toy vehicle to replace the pair of front wheels and work with the rear wheels for facilitating the change of direction.

In accordance with another embodiment of the present invention, the toy body is a robot toy body, which is equipped with two movable members: a pair of leg members. By means of the two-phase stepper motor, a desired gait for the toy robot is generated through a swing drive mechanism which includes a shaft, two cams and two guide plates attaching to the two leg members connected by said shaft, and a guide rod, the two ends of which are separatively placed in a guide slot formed on the guide plate.

In accordance with a further embodiment of the present invention, the toy body is a candy holder body, which equipped with one movable member: a spindle shaft, to which a candy is attached.

To have a better understanding of the invention reference is made to the following detailed description of the invention and embodiments thereof in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 a and 1 b are timing waveforms of a driving current of a method for controlling a two-phase stepper motor to various operational modes.

FIG. 2 is a schematic side view of a first embodiment of a two-phase stepper motor driven toy in accordance with the invention.

FIG. 3 is a timing waveform of driving signal to the two-phase stepping motor in “bounce mode 1” as shown in FIG. 2.

FIG. 4 is a schematic side view of a second embodiment of a two-phase stepper motor driven toy in accordance with the invention.

FIGS. 5 a and 5 b are a schematic side view of walking motion of the two-phase stepper motor driven toy as shown in FIG. 4.

FIG. 6 is a schematic side view of a third embodiment of a two-phase stepper motor driven toy in accordance with the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A two-phase stepper motor in accordance with the present invention can operate in “persistent mode”, “bounce mode 1”, “bounce mode 2” and “quiver mode” (see the provisional application No. 60/679,234, entitled “Method of Controlling Two-Phase Stepping Motor”, the disclosures of which are incorporated herein by reference in its entirety).

The operational modes of the two-phase stepper motor will be clarified from the following description with reference to the accompanying drawings.

The motor driving current may be generated by using a driving circuit which employs respective pulse width modulators for two poles of the two-phase stepper motor and a frequency divider controlling the modulators, with the their individual output currents interacted and combined to produce the motor driving current of the desired waveform.

For symmetrical case where duration of phase A equals duration of phase C and duration of phase B equals duration of phase D, the two-phase stepper motor will behave in different operational modes by varying the duration of the positive section, i.e. phase A, or the inactive section, i.e. phase B (FIGS. 1 a and 1 b).

It should be noted that the operational mode remains the same when the sum of phase A and phase B is approximately constant.

The driving signals may be asymmetrical for the two phases of the motor, in other words, the duration of A might differ from duration of C, or duration of B might differ from duration of D. In such case, if the sum of duration of A and duration of B is larger than the sum of C and D, duration of A and B will become dominant and determine the operational mode of the motor, and vice versa. If the sum of duration of phase A and duration of phase B is greater than the sum of duration of phase C and duration of phase D, the motor will operate according to the duration of phase A and phase B of the current driving signal.

The mark width (i.e. the width of active driving region) and/or space width (i.e. the width of inactive driving region, or from the falling edge of the acting driving region to the rising edge of the next active driving region) may be adjusted in a controlled manner to determine the behavior of the motor.

While operating in the “quiver mode”, the two-phase stepper motor rotates in a quivering manner with random output directions

While operating in the “bounce mode 1” or “bounce mode 2”, the two-phase stepper motor rotates in the opposite direction when rotary motion is obstructed.

While operating in the “persistent mode”, the two-phase stepper motor tends to rotate in the same direction when rotary motion is obstructed.

The variation in strength of current driving or in motor loading will shift the region of operational modes. The effect can be compensated by phase duration adjustment.

One of the methods to determine the mark width and space width for the operational modes comprises the steps of

A. firstly, the biased two-phase stepping motor is driven by a typical method in prior art;

B. an obstacle is inserted to block the rotary motion of the motor, which is in persistent mode and tends to rotate in the original direction;

C. the driving signal duty cycle is gradually reduced until a point where the motor rotation starts to bounce back, the motor is entering the bounce mode

D. the driving signal pulse width is further reduced until a point where the motor rotation starts to quiver or produce random rotation, the motor now enters the quiver mode.

When a two-phase stepper motor driven toy starts movement from rest, the driving circuitry generates electrical signals such that the two-phase stepper motor operates in “persistent mode” in order to overcome the static friction and inertia. After a reasonable period of time the toy gains velocity which permits the driving circuitry to drive the two-phase stepping motor into “bounce mode 1”. As a result, the toy will change into opposite direction upon collision with an obstacle.

The propelling speed of the toy can be varied by adjusting the period of the driving signal, as long as the motor remains in the same operational mode.

When the two-phase stepping motor is driven by symmetrical driving signals, the rotational speed will have to increase when switching from “persistent mode” to “bounce mode 1”. As a result, the movement of the toy appears unnatural which is unfavorable. “Velocity compensation” can be implemented by asymmetrical driving. Driving signals now become asymmetrical; for example, the positive cycle is always longer than the negative cycle, in such case, the positive cycle dominates and determines the mode of operation. When switching from “persistent mode” to “bounce mode 1”, the positive cycle is shortened, meanwhile the negative cycle is extended such that the sum of positive cycle and negative cycle remains unchanged. Since the period of the driving signal is constant, the velocity remains constant even the mode of operation has switched.

Referring now to the drawings wherein the showings are for purposes of illustrating preferred embodiments of the present invention only, and not for purposes of limiting the same. FIG. 2 provides a two-phase stepper motor driven toy consistent with a first embodiment of the present invention. In this embodiment, the two-phase stepper motor driven toy 10 comprises a toy vehicle body 11 which is mounted on a chassis equipped with a pair of front wheels 12 and a pair of rear wheels 13; a transmission mechanism 14 operatively coupled to the rear wheels 13; an electric drive means 15 for driving the rear wheels 13 via said transmission mechanism 14, which means includes a motor control circuitry 16 for generating electrical signals in accordance with preset modes and a two-phase stepper motor 17 electrically connected to said motor control circuitry 16 to selectably regulate the operational modes of the two-phase stepper motor 16 in response to the generated electrical signals for translating the rotational motion via said transmission mechanism 14 to actuate motion of the toy vehicle 10; and a battery power unit 18 for providing power to said drive means 15.

The toy vehicle is steered by the two-phase stepper motor 17, with the rear wheels 13 being operatively controlled by and coordinated with the two-phase stepper motor 17 in their movements. The control and coordination of the movements of the rear wheels 13 cause the toy vehicle to move in a forward direction or in a backward direction when encountering an obstacle.

When the battery power unit 18 is activated, the two-phase stepper motor 17 enters the “persistent mode” to actuate movement of the toy vehicle through the transmission mechanism 14 which may be a conventional gear assembly. The gear assembly is mechanically connected to two drive shafts, one of which is secured to the rear wheels 13 of the toy vehicle body 11 and another of which is secured to the two-phase stepper motor 17, whereby the rear wheels 13 are driven by the two-phase stepper motor 17 to move. After gaining velocity, the motor control circuitry 16 drives the motor 17 into the “bounce mode 1” and the toy vehicle proceeds in the “bounce mode 1” until it encounters an obstacle, at which point an opposite angular momentum generates on the rear wheels and translates to the two-phase stepper motor through the transmission mechanism 14. In FIG. 3, a timing waveform of driving signal to the two-phase stepping motor in “bounce mode 1” is illustrated, given the holding torque to the wheel movement is about 2.5 g-cm, the gear ratio is 1:30 and the electrical current applied to a coil of 2500 turns is about 12 mA.

According to the behavior in the “bounce mode 1”, the motor 17 rotates in an opposite direction, as a result, the toy vehicle bounce back and automatically changes its direction of movement, i.e. the toy vehicle continues its movement in an opposite direction.

When the motor 17 operates in the “quivering mode”, the toy vehicle demonstrates trembling motion and appears as the engine of the vehicle going to break down.

As an alternative, the pair of front wheels may be substituted by a freely rotating wheel, which is arranged centrally and somewhat forwardly underneath the chassis of the toy vehicle to work with the rear wheels such that the backward direction deviates from the line of axis of the forward direction. This freely rotating wheel continuously engages the ground and is operative to cause said change of direction.

Referring now to FIG. 4, a two-phase stepper motor driven toy consistent with a second embodiment of the present invention is shown. In this embodiment, the two-phase stepper motor driven toy 20 is a toy robot, which comprises a toy robot body 21 equipped with a pair of leg members 22 that are capable of stably moving forward and backward; a transmission mechanism 23 operatively coupled to the leg members 22; an electric drive means 24 for driving the leg members 22 via said transmission mechanism 23, which means includes a motor control circuitry 25 for generating electrical signals in accordance with preset modes and a two-phase stepper motor 26 electrically connected to said motor control circuitry 25 to selectably regulate the operational modes of the two-phase stepper motor 26 in response to the generated electrical signals for translating the rotational motion via said transmission mechanism 23 to actuate motion of the toy robot 20; and a battery power unit 27 for providing power to said drive means 23.

The toy robot 20 is driven to walk by the two-phase stepper motor 26 which is cooperatively engaged to the leg members 22 and operative to reciprocally cause the leg members to move in a forward direction or in a backward direction when encountering an obstacle. The toy robot body 21 is configured such that when one leg member 21 is driven to move up and forward, the other leg member 21 interconnected to said driven leg member by a fixed shaft 28 is moved in unison therewith.

To realize the stable walking motion of the toy robot 20, the transmission mechanism 23 of the toy robot is comprised of a conventional gear assembly and a swing drive mechanism, wherein the gear assembly is connected respectively to the two-phase stepper motor and the swing drive mechanism. The swing drive mechanism includes a rotating shaft which connects two cams and two guide plates attaching to the two leg members and a guide rod, the two ends of which are separatively placed in a guide slot formed on the guide plate. The two leg members 22 are attached to the opposite guide plates. When the fixed shaft 28 is driven by the two-phase stepper motor 26 via the gear assembly and rotates, the two leg members alternatively steps forwards/backwards by means of translating from rotation of the eccentric cam into up/down and back/forth swing motion, thus allowing for generation of a desired gait for the toy robot.

When the battery power unit 27 is activated, the two-phase stepper motor 26 enters the “persistent mode” to actuate movement of the toy robot through the transmission mechanism 23. After gaining velocity, the motor control circuitry 25 drives the motor 26 into the “bounce mode 1” and the toy robot stably walks in the “bounce mode 1” until it encounters an obstacle, at which point an opposite angular momentum generates on the leg members 22 and translates to the two-phase stepper motor 26 through the transmission mechanism 23.

It can be seen from FIGS. 5 a and 5 b, the robot has its central of gravity placed on the left leg member. When driven to move, the swing drive mechanism brings the right leg member to move upwards and forwards (see “A” state of FIG. 5 a). In “B” state of FIG. 5 a, the central of gravity is transferred from the left leg member to the right leg member. Simultaneously, the swing drive mechanism brings the left leg member to move upwards and forwards, and the right leg member to move downwards. In “C” state of FIG. 5 a, the central of gravity is placed on the right leg member and the left leg member moves downwards. With the central of gravity shifting between the two leg members 22 alternatively, the toy robot proceeds to step forward until it encounters an obstacle.

According to the behavior in the “bounce mode 1”, the motor 26 rotates in an opposite direction, as a result, the toy vehicle bounce back and automatically changes its direction of movement, i.e. the toy robot continues its walking in an opposite direction.

Referring lastly to FIG. 6, a two-phase stepper motor driven candy holder 30 consistent with a third embodiment of the present invention is shown. One of candy holders currently known in the prior art is disclosed in U.S. Pat. No. 5,209,692 issued to Coleman et al. The third embodiment in accordance with the present invention provides the candy holder 30 similar in structure to that disclosed in the Coleman et al patent, but significantly differing in that the present candy holder 30 employ the use of an electric drive means 34 for rotating the spindle shaft 32 via a transmission mechanism 33, which means includes a motor control circuitry 36 for generating electrical signals in accordance with preset modes and a two-phase stepper motor 35 electrically connected to said motor control circuitry 36 to selectably regulate the operational modes of the two-phase stepper motor 35 in response to the generated electrical signals. The use of the miniature two-phase stepping motor allows for the manufacture of the candy holder of the present invention in a size and cost substantially less than those of the candy holder disclosed in the Coleman et al patent.

In operation, the candy 31 is placed in the mouth of a person desiring to consume this candy. The spindle shaft 32 which when driven for rotation, rotates the candy 31 attached thereto in a forward or reversible direction. When activating the candy holder 30 by turning-on the battery power unit 37, the two-phase stepper motor 33 in the drive operates in the “persistent mode” and then switch into the “bounce mode 1”. When the candy is sucked by force, an opposite angular momentum generates on the spindle shaft 31 and translate through the transmission mechanism 34 to the two phase stepper motor 33. According to the behavior in the “bounce mode 1”, the motor rotates in an opposite direction to drive the spindle shaft for rotation, which in turn rotates the candy in an opposite direction.

While the invention has been particularly shown and described with reference to three preferred embodiments: a toy vehicle, a toy robot and a candy holder, it will be understood by those skilled in the art that the foregoing and other changes in form and details, e.g. those of toy motor cycles, toy aeroplanes etc., may be made therein without departing from the spirit and scope of the invention. 

1. A two-phase stepper motor driven toy comprising: a toy body; at least one movable member movably mounted to said toy body; a transmission mechanism operatively coupled to said at least movable member; an electric drive means for driving said at least movable member via said transmission mechanism; a battery power unit for providing power to said drive means; wherein said electrical drive means includes: a motor control circuitry for generating electrical signals in accordance with preset modes; and a two-phase stepper motor, which is electrically connected to said motor control circuitry to selectably regulate the operational modes of the two-phase stepper motor in response to the generated electrical signals, for translating the rotational motion via said transmission mechanism to actuate motion of said at least movable member of the toy.
 2. A two-phase stepper motor driven toy in accordance with claim 1 wherein the motor control circuitry is a micro control unit or a microprocessor.
 3. A two-phase stepper motor driven toy in accordance with claim 1 wherein the motor control circuitry is programmed to operate the two-phase stepper motor to move said at least one movable member in a manner permitting said movable member to be moved in a forward or backward direction.
 4. A two-phase stepper motor driven toy in accordance with claim 1 wherein the two-phase stepper motor is operating at a speed which can be varied by adjusting the period of the electrical signals generated from the motor control circuitry.
 5. A two-phase stepper motor driven toy in accordance with claim 1 wherein the two-phase stepper motor is reversible to drive the toy depending on the periods and pulse widths of the electrical signals.
 6. A two-phase stepper motor driven toy in accordance with claim 1 wherein the transmission mechanism includes a gear assembly including two gears respectively connected to two drive shafts, said two drive shafts being secured respectively to said at lest movable member of the toy body and the two-phase stepper motor, whereby said at lest movable member is driven by the two-phase stepper motor through the gear assembly.
 7. A two-phase stepper motor driven toy in accordance with claim 1 wherein the toy body is a toy vehicle body, which is mounted on a chassis equipped with four movable members: a pair of front wheels and a pair of rear wheels.
 8. A two-phase stepper motor driven toy in accordance with claim 7 wherein a freely rotating wheel is arranged centrally and somewhat forwardly underneath the chassis of the toy vehicle to replace the pair of front wheels and work with the pair of rear wheels.
 9. A two-phase stepper motor driven toy in accordance with claim 1 wherein the toy body is a robot toy body, which is equipped with two movable members: a pair of leg members.
 10. A two-phase stepper motor driven toy in accordance with claim 9 wherein a desired gait for the toy robot is generated by means of the two-phase stepper motor through a swing drive mechanism.
 11. A two-phase stepper motor driven toy in accordance with claim 10 wherein the swing drive mechanism includes a shaft, two cams and two guide plates attaching to the two leg members connected by said shaft, and a guide rod, the two ends of which are separatively placed in a guide slot formed on the guide plate.
 12. A two-phase stepper motor driven toy in accordance with claim 1 wherein the toy body is a candy holder body, which equipped with one movable member: a spindle shaft to which a candy is attached.
 13. A two-phase stepper motor driven toy in accordance with claim 1 wherein the battery used in the battery power unit is a button cell. 